Studies utilizing fresh lymphoma cells or derived cell lines are carried out with the primary objectives of understanding lymphomas in the context of normal lymphocyte differentiation, and identifying the normal counterpart cells of specific malignant lymphomas. Detailed phenotypic characterization of tumors and cell lines is carried out and studies of immunoglobulin secretion and the characteristics of the secreted molecular species are in process. The development of heteroantisera and hybridoma antibodies with specificity for non-endemic Burkitt's lymphoma is proceeding and has led to the recognition that American tumors differ phenotypically from African tumors. Characterization of these antigenic differences is in process. Studies of the biological effects of various EBV strains on normal lymphocytes continue.